Fuse bushing with sealing means providing hotstick changeout of fuse

ABSTRACT

A fuse bushing for electrical apparatus such as a transformer. The bushing receives a fuse such as a current limiting fuse and is sealed at its outer end. The sealing means includes a cover with an O-ring gasket, the cover having a member extending into the bushing which is connected to the outer end of the fuse. A contact plate is provided fitting over the cover and having two captive eyebolts which are threaded into the flange mounted on the end of the bushing. The eyebolts may be operated by a hotline tool and when tightened into the flange cause the contact plate to contact the cover, firmly holding such cover into the bushing thereby sealing the bushing by the O-ring. A vent device is provided in the cover for direct venting of fuse gases on operation of the fuse.

United States Patent .1191

Charbonneau et al.

[111 3,798,583 [451 Mar. 19, 1974 Assignee: General Electric Company Filed: June 23, 1972 Appl. No.: 265,568

Int. Cl. H01h 85/02 Field of Search 337/201, 202, 203, 204, 337/207, 249, 250, 281,2, 219, 180, 181;

References Cited UNITED STATES PATENTS 2/1952 Ackermann 337/28 UX 6/1961 Linton 1 337/201 X 12/1965 Linton 337/201 X 10/1971 Monico 174/145 3,486,154 12/1969 Seagrave et a1 337/187 Primary Etaminer-Harold Broome Assistant Examiner-F. E. Bell Attorney, Agent, or Firm--Francis X. Doyle [57] ABSTRACT A fuse bushing for electrical apparatus such as a transformer. The bushing receives a fuse such as a current US. Cl. 337/202, 174/145 1 limiting fuse and is sealed at its outer end. The sealing means includes a cover with an O-ring gasket, the cover having a member extending into the bushing which is connected to the outer end of the fuse. A contact plate is provided fitting over the cover and having two captive eyebolts which are threaded into the flange mountedon the end of the bushing. The

eyebolts may be operated by a hotline tool and when tightened into the flange cause the contact plate to contact the cover, firmly holding such cover into the bushing thereby sealing the bushing by the O-ring. A vent device is provided in the cover for direct venting of fuse gases on operation of the fuse.

6 Claims, 4 Drawing Figures FUSE BUSHING WITH SEALING MEANS PROVIDING HOTSTICK CHANGEOUT OF FUSE BACKGROUND OF THE INVENTION replacement of the fuse.

In electrical apparatus, such as transformers and the like, various types of fuses are used to protect such apparatus from overcurrent conditions. When such fuses have operated, itis desirable to be able to replace the fuses without opening the electrical apparatus, which as is well known is generally sealed in a tank or container. Of course, it is also necessary that the fuses be sealed from the environment to prevent moisture or the like from damaging the fuse. See, for example, US. Pat. Nos.3,47l ,816 and 3,480,898 which show bushing type devices with fuses therein and one form of sealing means to prevent entry of moisture into the bushing device which moisture might interfere with the proper operation of the fuse.

In many types of present day electrical systems, surface or subsurface transformers are used in a loop feed distribution system. Each transformer is provided with two energized lines such that it may be energized from either of two electrical sources or the electrical source energizing it may be continued onto the next transformer in the loop feed system. In these distribution systems, each transformer must have two high voltage bushings or the one high voltage bushing must be provided with a terminal or contact device which can carry a pair of energized cables such that the transformer may be energized from either of two sources. One such bushing and terminal device is shown, for example, in application Ser. No. 204,095 filed Dec. 2, 1971 for High Voltage Bushing with Removable Connector and Locking Plate, now US. Pat. No. 3,721,946 which application is assigned to the same assignee as this application. One problem with such loop feed systems is that the terminal device carrying the energized cables must be removed with hotline tools. This creates a problem in the sealing of the bushing after removal and replacement of the fuse, since it is very difficult to provide adequate sealing in the bushing by using hotline tools. This is especially true in surface type transformers, such as pad mounted transformers, where the bushings are mounted horizontally. It is extremely difficult to provide an adequate seal in the cover of the horizontal bushing. It is also considered desirable to be able to utilize a portable loadbreak device when removing the energized-cables to prevent breaking load between the contact plate carrying the energized cables and the cover of the bushing.

It is, therefore, one object of this invention to provide a novel fuse bushing with a removable contact plate where such contact plate is used to help seal the bushing.

A still further object of this invention is to provide a novel sealed fuse bushing having a contact device which is removably attached to the bushing flange and wherein such contact device is slotted toallow removal with a portable loadbreak device connected between such contact plate and the outer end of the bushing.

Yet another object of this invention is to provide a novel sealed fuse bushing wherein the fuse may be replaced by hotline tools and the bushing resealed by use of such tools.

SUMMARY OF THE INVENTION Briefly, in one form, this invention provides a sealed fuse bushing in an electrical apparatus. The exterior end of the bushing is closed by a cover which has sealing means to prevent entry of moisture into the bushing. A contact plate or member is attached to the end flange of the bushing holding the cover in sealed relation to the bushing and providing means for attaching energized cables to the bushing. Means are provided on the contact plate such that a portable loadbreak device may be connected between the cover and the contact member to allow removal of the contact member from the cover without breaking the circuit therebetween.

The invention which is sought to be protected will be particularly pointed out and distinctly claimed in the claims appended hereto. However, it is believed that this invention and the manner in which various objects and advantages are obtained as well as other objects and advantages thereof may be better understood by reference to the following detailed description of a preferred embodiment, especially when considered in the light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial sectional view of a high voltage fuse bushing showing the hotline tool removable plate and bushing cover according to a preferred embodiment of this invention;

FIG. 2 is an enlarged sectional view of a portion of the bushing of FIG. 1 showing the sealed cover and the contact plate of this invention in greater detail, such section being taken on the line 2-2 of FIG. 3;

FIG. 3 is an end view of the bushing cover and contact member according to the preferred embodiment of this invention and;

FIG. 4 is an exploded perspective view of the bushing cover and contact member showing further details of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the preferred form of this invention, a fuse bushing is attached to the wall of an electrical apparatus and a removable fuse is mounted therein acting as an electrical connector or conductor from one end of the bushing to the other. A cover member is provided, secured to one end of the fuse and having sealing means to seal the exterior of the bushing. A contact plate is attached to a bushing flange and holds the cover in sealed relation to the bushing. A more detailed description of the preferred embodiment will be made with reference to the accompanying drawings in which like numerals are used to indicate like parts throughout the various views.

Referring first to FIG. 1, a fuse bushing 10 is shown secured to a wall or cover 12 of an electrical apparatus (not otherwise shown). The bushing 10 is held to the wall 12 by means of bolts 14 which extend through flange 16 on the bushing 10 and into the wall 12, as shown. Obviously, bushing 10 could be secured to wall 12 in any other desired manner, such as by welding, clamping or the like. It will be understood that wall member 12 forms a portion of a tank or other type of container for an electrical apparatus and that the flange 16 is attached to the exterior of wall 12 of the tank of such apparatus. As is well known, the electrical apparatus is usually sealed in the tank and the tank is normally filled with a dielectric fluid such as, for example, transformer mineral oil, which provides insulation and cooling for the electrical apparatus.

Bushing is provided with an internal contact 18 which extends through the end of the bushing 10 providing an internal contact 20 for the electrical apparatus. A fuse member 22, such as a current limiting fuse, is mounted in bushing 10 and has an end 24 to which is secured a contact 26. Contact 26 has a bullet shape and forms a bayonet type sliding connection with contact 18. To aid in aligning contact 26 with contact 18, a plastic centering disk or shield 28 is provided, secured to end 24 of fuse 22 by contact 26. On the exterior end of bushing 10, a flange 30 is provided secured by clamping ring 32 and sealed thereto by a gasket 34 which is sealed between the flange 30 and the bushing 10 and held secure by the clamping ring 32. (See FIG. 2). A cover member 36 fits against flange 30 and has a portion 38 which is against the outer portion of the flange 30 while another portion 40 extends into the opening of the flange 30, as is shown in FIG. 2. An extension 42 on cover 36 is hollow and provided with a collar 44 which fits over the outer end 46 of the fuse 22, as can best be seen in FIG. 1. As will be understood, extension 42 may be formed integrally with the cover 36, or it may be of various lengths which may be assembled with cover 36 according to the length of the bushing 10 and the length of the fuse 22.

FIGS. 2, 3 and 4 show the invention in greater detail, particularly the cover 36. Referring first to FIG. 2, it can be seen that the cover 36 has an opening extending from the fuse 22 through collar 44, extension 42, and portion 40 to a depression 48 in portion 38 of the cover 36. An automatic pressure relief valve 50 is provided in depression 48 threaded into portion 40 as shown. As will be readily understood, when the fuse 22 operates, that is, when it is fused or blown, gases may be generated within the bushing 10. To prevent any damage to the bushing, the pressure relief valve 50 is provided to automaticlly release the gas pressure within bushing 10 and to then resea] after it has released such gases. Openings 42a are provided in extension 42 of the cover 36 to allow any gases around fuse 22 to flow to the relief valve 50 and to actuate such relief valve.

Cover 36 is provided with a captive O-ring seal 52 which fits into a groove 54 on the portion 40 of cover 36. This can be readily seen in the exploded view of FIG. 4. The inner edge 56 of flange 30 is beveled as is best shown in FIG. 4 to receive O-ring 52 and provide a seal between the cover 36 and the flange 30. A terminal or contact plate 58 is provided which fits against cover 36 and is secured to the flange 30. As can be seen in FIGS. 2 and 4, flange 30 is provided with threaded openings 60,62 while the contact plate 58 has a pair of captive eyebolts 64,66 which may be threaded into the openings 60,62 by means of hotline tools. In the preferred embodiment, the O-ring 52 and the bevel 56 are selected such that a moisture seal is provided when portion 38 of cover 36 is in contact with flange 30. Thus, cover 36 is sealed in the flange 30 by eyebolts 64 and 66 being tightened until portion 38 of cover 36 bottoms against the outer edge of flange 30, as is shown in FIG. 2.

In order to enable removal of cover 36 and fuse 22 connected thereto, an eye member 68 is mounted on the exterior of cover 36. As can be seen, particularly in FIG. 4, eye 68 has a hook portion 70 which is secured to plate 72 while plate 72 is provided with an opening 72a which registers with depression 48 of cover 36 to allow valve 50 to release gas from within bushing 10. A pair of screws 74,76 are provided for securing eye 68 to cover 36.

As can be seen, especially in FIGS. 3 and 4, the contact plate 58 extends beyond cover 36 and flange 30 as indicated by the extension 78. Extension 78 is provided with a pair of slots 80,82 which will receive eyebolt cable connectors (not shown). Stops 84 and 86 are provided on the back of extension 78 and at the inner end of slot and 82, respectively, to contact the nut on the eyebolt cable connector and allow such connector to be firmly tightened to extension 78 by hotline tools. The contact plate 58 is also provided with a keyhole opening 88 which fits around eye 68 so that contact plate 58 may make a firm electrical connection with the cover 36. Also by means of the keyhole" opening 88, a portable loadbreak device may be easily connected between the hook 70 of the eye member 68 and the contact plate 58 allowing removal of such contact plate 58 without breaking load between the plate 58 and the cover 36.

From the above discussion, it is believed that those skilled in the art will readily understand the novel fuse bushing cover and contact plate of this invention. The cover 36 with fuse 22 can be readily handled by a shotgun" or other hotline tool secured to the eye member 68, as indicated in phantom view in FIG. 1. The fuse 22 may be inserted into the bushing 10 horizontally or vertically, or any angle in between, and the plastic guide 28 will aid in guiding contact 26 of fuse 22 into contact 18 of the bushing 10. Cover 36 may then be released and the contact plate 58 picked up by a hotline tool by either of the eyebolts 64 or 66. One of these eyebolts will be engaged with one of the threaded openings 60 or 62 in the flange 30. The contact plate 58 may then be rotated by the other eyebolt which will then be engaged with the other threaded opening in flange 30. The contact plate 58 will then be pulled securely against cover 36 by tightening the eyebolts 64,66 thus firmly seating and sealing the cover 36 into the flange 30 on the bushing 10. Obviously, the fuse 22 may be removed and replaced in a similar manner by using hotline tools.

While there has been shown and described the present preferred embodiment of the invention, it will, of course, be apparent to those skilled in the art that various changes may be made in some of the constructional details without departing from the spirit and scope of the invention, particularly as it is set forth in the appended claims.

What is claimed as new and which it is desired to secure by Letters Patent of the United States is:

1. A sealed fuse bushing for an electrical apparatus comprising a bushing member, an internal contact on the internal end of said bushing, a flange secured to the outer end of said bushing, a cover member, a fuse removably secured at one end to said cover and extending into said bushing, a contact on the other end of said fuse, said fuse contact making an electrical connection to said internal contact of said bushing, a contact plate, means removably securing said contact plate to said flange and holding said cover against said flange, and sealing means on said cover between said cover and said flange sealing said bushing.

2. A sealed fuse bushing as set forth in claim 1 in which said sealing means on said cover is an O-ring fitting in a groove on said cover and firmly seated against said flange.

3. A sealed fuse bushing as set forth in claim 2 in which said flange is provided with a beveled edge and said O-ring on said cover seals against said beveled edge.

4. A sealed fuse bushing as set forth in claim 1 in which said means securing said contact plate to said flange comprises a pair of captive eyebolts mounted in said contact plate, said eyebolts being threaded into openings in said flange.

5. A sealed fuse bushing as set forth in claim 1 in which said cover member is provided with an eye member, said eye member extending through an opening in said contact plate, said eye member adapted to receive hotline tools for removing said cover from said bushing.

6. A sealed fuse bushing as set forth in claim 1 in which said means removably securing said fuse to said cover is a hollow extension member attached to said cover and to said fuse, said hollow extension member being provided on the outer end with an automatic pressure relief device which opens to allow any gases built up in said bushing to pass through said cover, said automatic pressure relief device then rescaling. 

1. A sealed fuse bushing for an electrical apparatus comprising a bushing member, an internal contact on the internal end of said bushing, a flange secured to the outer end of said bushing, a cover member, a fuse removably secured at one end to said cover and extending into said bushing, a contact on the other end of said fuse, said fuse contact making an electrical connection to said internal contact of said bushing, a contact plate, means removably securing said contact plate to said flange and holding said cover against said flange, and sealing means on said cover between said cover and said flange sealing said bushing.
 2. A sealed fuse bushing as set forth in claim 1 in which said sealing means on said cover is an O-ring fitting in a groove on said cover and firmly seated against said flange.
 3. A sealed fuse bushing as set forth in claim 2 in which said flange is provided with a beveled edge and said O-ring on said cover seals against said beveled edge.
 4. A sealed fuse bushing as set forth in claim 1 in which said means securing said contact plate to said flange comprises a pair of captive eyebolts mounted in said contact plate, said eyebolts being threaded into openings in said flange.
 5. A sealed fuse bushing as set forth in claim 1 in which said cover member is provided with an eye member, said eye member extending through an opening in said contact plate, said eye memBer adapted to receive hotline tools for removing said cover from said bushing.
 6. A sealed fuse bushing as set forth in claim 1 in which said means removably securing said fuse to said cover is a hollow extension member attached to said cover and to said fuse, said hollow extension member being provided on the outer end with an automatic pressure relief device which opens to allow any gases built up in said bushing to pass through said cover, said automatic pressure relief device then resealing. 